Google is scrapping information from you from your phone, your browser, your emails, your searches. They track you at scale. They track millions of people at scale! Using all that data + data mining + their AI capabilities + psychologists, they are able to generate incredibly detailed models of each individual. Their models will have predictive power. And that is what their whole business is about - how to best monetise you for their customers and shareholders. (Of course Apple, Facebook, Amazon etc are trying to do the same.)
So, think about it, they have all this information, and will continue to collect it, but won't give you an indication on what they are collecting - why would they do that? Its because we are reaching a data equivalent of the uncanny valley - where google (et al) know you better than you know yourself, but don't want you to know that!